Reed switch adjustment



March 16, 1965 B. MISHELEVICH ETAL 3,174,008

REED SWITCH ADJUSTMENT Filed Aug. 15, 1962 wwf/m0123456? United Sltates Patent O M 3,174,ti(93 REED SWITCH ADJIIUSTMENT Benjamin Mishelevich and Edward G. Tutle, Galion, Ohio, assignors to North Electric Company, Galion, Ohio, a corporation of Uhio Filed Aug. 15, 1962, Ser. No. 216,995 3 Claims. (Cl. 20d-87) The present invention relates to reed relay adjustment, and more particularly to means for effecting precise adjustment of reed switches.

Since their introduction a Lfew years ago, reed relays have become practically commonplace because of their small size, reliability, long life, speed of operation, low power requirements, and moderate cost. They are employed especially in connection with transistors, being widely used in data processing systems, communication systems, missile and satellite ground control, and in certain circuits of electronic computers. These relays can be produced with various operating characteristics, depending upon the particular application for which they are intended. The relays may also vary in complexity, from a single reed switch operated by a single coil to constructions employing several coils and several reeds, some types being of highly rened construction. Of course, the more complex types of reed Irelays are more expensive to manufacture than the simpler kinds. Even the simpler types, however, may involve an increase in cost, depending upon the degree of precision desired or required in operation. In other words, as may be expected, greater precision involves increased manufacturing costs.

By the present invention, reed relays of relatively low cost, not built to provide any great exactitude in operation, can be adjusted to operate with a high degree of precision by adjustment of the operating charcteristics of the reed switch means employed therein. This allows relays deviating from an intended or desired operating level or value to be adjusted, or corrected, quickly and easily, and at low cost. Thus relays which otherwise would have lto be rejected for the desired use may be employed as intended, and the loss involved in discarding reed switches not coming within the permitted tolerances in operation is saved. Similarly, reed switches not designed for precise operation may be converted into switches operating within a selected time interval, for example, and reed switches designed for operation at a given value may be adjusted to operate at another value. Flexibility and interchangeability are thus imparted to reed relays, and a great reduction in cost is eliected by eliminating the need to build the relays or the reed switches thereof as precision devices. Any device or arrangement for adjusting the operation of reed relays, or more precisely of the reed switches of such relays, must of course be effective, and it must also be inexpensive, since the cost must be appreciably less than the difference in cost between a carefully made, precisely operating relay and one made to lower standards. The present invention meets these requirements, as has already been indicated.

It is an object of the invention to provide reed switch adjustment means allowing of close control of operation of the switch.

Another object is the provision of means for adjusting a reed switch which may be simply and quickly applied and adjusted and positively held in the adjusting position.

Another object is the provision ot .reed switch adjustment means readily fixed in adjusted position.

A further object is the provision of reed switch adjustment means readily adjusted to a desired position and 3,174,098 Patented Mar. 16, 1965 ICC held in such position, and readily moved from such adjusted position to another adjusted position and held in the second position.

Another object of the invention is to provide means for adjusting a reed switch which is inexpensive, yet effective, positive, and reliable in operation.

Other `and further objects, advantages, and features of the invention will be apparent to those skilled in the art from the following detailed description, taken in conjunction with the accompanying drawings:

FIGURE l is a longitudinal sectional view through a reed relay construction employing one form of the invention;

FIGURE 2 is a cross-sectional view taken substantially as indicated by the line 2 2 of FIGURE l;

FIGURE 3 is a view similar to FIGURE l, but showing another embodiment of the invention;

FIGURE 4 is a view similar to FIGURES l and 3, but showing still another embodiment;

FIGURE 5 is an enlarged side elevational view of a reed switch such as shown in FIGURES 1 to 4 inclusive, with an adjusting element secured thereon;

FIGURE 6 is a cross-sectional view taken substantially `as indica-ted by the line 6-6 of FIGURE 5;

FIGURE 7 is a sectional view similar .to FIGURE 2, but illustrating a relay in which two reed switches are employed with a solenoid; and

FIGURE 8 is a graph showing voltage and time curves of a typical reed relay employing the invention, with the adjusting means positioned at difieren-t locations.

Referring rst to FIGURES l to 2 of the drawings, there is shown a reed relay generally designated 10, comprising a solenoid il from the opposite ends of which extend leads I2 and i3 for connection to suitable terminals or conductors of a circuit by which the solenoid 11 may be energized. Disposed within the solenoid is a reed switch, generally designated 14, comprising in this instance a lglass envelope 15 within which extend a pair of resilient reeds or contacts 16, the `free ends of which are in overlapped relation and the fixed ends of which are mounted in the ends of the envelope 15, which is sealed about the Contact members. The contact members 16 are of magnetic material such as a nickel-iron alloy having high permeability and low residual characteristics. The free or contact end portions of the contact members are plated or otherwise surfaced with a precious metal, as is well known in the art. The envelope 15 is lled with an inert gas, or alternatively may be evacuated to a high degree, to avoid corrosion of the contacts. Soldered or otherwise suitably connected to the fixed ends of the Contact members 16, within the sealed ends of the envelope 15, are conductors 17 of copper or other nonmagnetic material extending externally of the envelope to provide for connection of the relay in the circuit which it controls.

It is to be noted that if desired only one of the contacts i6 need be resilient, or that the contacts may otherwise be arranged for relative movement to engage or disengage. Similarly, the contacts may parallel each other. In other words, the particular manner in which the contacts cooperate to open and close the circuit controlled thereby does not affect the invention, so long as the contacts are cooperable as indicated and operate in response to magnetic flux. It is also pointed out that the contacts need not be entirely, but only principally or largely, composed of magnetic material. For practical purposes, however, the contacts may be described as of magnetic material, and they are so referred to herein. The contacts may have an interface of non-magnetic material. For example, the contact areas may be wetted by mercury in a known manner, and in addition or alternativeair/aoco 3 1y, may have a contact material such as mentioned hereinabove coated or dilused thereon.

v Instead of employing an inert gas, or high vacuum, as -its contained atmosphere to prevent contact corrosion involving oxidation, the switch reed envelope may enclose an atmosphere of any gas suitable for preventing corrosion and pitting of the contacts from any particular cause. Thus dry or substantially dehydrated air may be contained in the switch envelope if, for example, it is desired to protect the contacts against moisture. The invention is not limited to use with reed switches emlploying a non-oxidizing atmosphere, since any desired corrosion-preventing or minimizing atmosphere may be employed. In fact, it is not necessary that the contacts be enclosed in any special atmosphere.

The relay l@ is illustrated as mounted on a base i8, enclosed by a shroud or casing 19 having a semi-cylindrical portion tting closely over the solenoid 1l with planar side walls extending to the base, a plate 19a being disposed between the side walls and under the solenoid, so that the coil and switch are surrounded by the two parts of the casing, Lugs It9b project from the walls and are bent under the base 13, being engaged in suitable edge notches in the base, to secure the casing and relay on the base. The relay might be otherwise mounted, as for example by soldered connections of the leads 12 and 13 and conductors i7 to the contact points of a printed circuit board, such board then constituting the mounting base for the relay. The casing 19, however, is formed of magnetic material so as to provide a magnetic and electrostatic shield t`or the relay and increase the range and sensitivity of the adjustment, as hereinafter explained more fully. A second shielding casing M9 is shown in dotted lines in FEGURES 1 and 2 in the form of an open-sided rectangular box of magnetic material enclosing the relay and casing 19. A plate 119e of magnetic material may close the open side of the casing M9, if desired. Additional similar casings might be provided for additional shielding, if desired.

In the present instance, the relay employs form A contacts, that is, contacts which are normally open and are closed upon energization of the solenoid so as to complete the circuit controlled by the relay. The magnetic iield established upon energization of the solenoid 1l iinds an easy flux path in the reeds or contact members i6, and the tiux thus passes through the contact members for a portion of its circuit, causing the contact end portions to be drawn together into conductive engagement, so as to close the relay. The relay may, instead of the normally open type illustrated, be of a normally closed type, in which energization of the solenoid effects separation of the contacts, or of a make-and-break or breakbefore-make type, if desired, as is known in the art. lt will be understood that for simplicity the invention is disclosed as incorporated in a single-coil, single-reed relay, except for the embodiment illustrated in FIGURE 7, but is fully applicable to complicated multi-coil, multireed relays.

An adjusting member 2@ is provided to vary the operation of the relay. The adjusting member comprises a strip of magnetic material disposed in longitudinally overlying relation to the envelope l and having formed preferably integrally therewith at one end a split ring portion 2LH. resiliently clamping about the envelope to serve as a guide and retaining means for the adjusting member as well as forming a major element or the member. The opposite end of the strip projects out of the coil 11, and has an upwardly bent ear or lug 22 which has a threaded aperture therethrough for cooperation with a screw 23 supported in parallel relation with the adjusting member 2@ by means of a bracket 242- secured on the base i8. In the present case, the bracket 2d is shown as of general L-shape, with one leg extending upwardly from the base and a horizontal leg extending from the upper end of the first leg toward the coil, and having a depending projection 2.5. The screw 23 projects through longitudinally aligned apertures in the upstanding leg of the bracket and the depending projection 2S, for free rotation therein, and is held against longitudinal movement in any suitable manner, as by a conical enlargement 26 on the end of the screw at the depending projection 25, and a head 27 fastened on the other end of the screw engaging against the upright leg of the bracket 24. The head 27 may be knurled, or provided with a tool-engaging slot or other means to facilitate rotation of the screw. it will be evident that turning of the screw 23 in one direction or the other by means of the head 27 will cause shifting of the adjusting member 2@ longitudinally of the reed switch ll4 to a selected position. The member 20 is shown in a position with the split ring portion 2l encircling and centered relative to the contact ends of the contact members t6. Suitable means may be provided to secure the adjusting member in the selected adjusted position, as for example a lock nut 2S on the screw 23 engageable against the upright leg of the bracket 24. A protective casing, similar to the casing 119 shown in dotted lines but not necessarily of magnetic material to provide shielding, may be provided to enclose the relay lil, with an aperture affording access to the screw head 27 from lthe exterior.

The adjusting member Ztl diverts a portion of the magnetic ux generated upon energization of the solenoid 11 from the circuit or path partially defined by the contacts 16 to` another path or circuit partially defined by the adjusting member. Actuation of the contact members is thus modiiied from what it would be in the absence of the adjusting member Ztl. The adjusting member is secured in the selected position corresponding to the desired operating characteristics of the relay, to make sure that the )adjusting member will not be moved unintentionally or inadvertently, or under the iniuence of vibration or like conditions, by means of the lock nut 28 or other locking means which may be employed. Undesired variation in the operating characteristics of the relay is thus avoided, once the selected adjustment has been made. lf the relay 10 is to be enclosed in a casing, with only the head 27 of the screw :accessible for effecting or changing the adjustrnent, as by engagement of la screwdriver in a slot thereof, suitable locking means may be provided exterior- 1y of the casing to` engage in the screwhead slot and thus hold the screw against rotation. Of course, many other means might be employed for securing the adjusting member 2t) in the desired position. The relay construction as illustrated in FIGURES 1 and 2 provides very precise control of the operating characteristics of the relay by means of the adjustment member 20, under the action of the screw 23.

The arrangement employing the adjusting screw 23 provides smooth movement of the adjusting member along the reed switch 14, and provides for easy changing of the adjustment when desired. It will, however, be under-- stood that other means may be employed for adjusting the member Ztl, if desired. It will also be understood that if desired means may be provided for adjusting the member 2t) laterally of the reed switch i4 as by forming the upstanding leg of the bracket 2d in two overlapping parts, with a known type of slot and clamping screw arrangement to allow vertical adjustment of the upper portion of the bracket, and hence of the adjusting member 2t), for a limited distance -to permit location of the adjusting member in a desired position between` the interior of the solenoid il and the exterior of the envelope 15. It will also be understood that it is not necessary to the invention that the operating characteristics` of the relay be variably adjustable, since the invention contemplates permanent adjustment of the relay to acln'eve desired operating characteristics of the relay substantially throughout its life, or at least for long periods so that a change in the adjustment is not often necessary.

atrasos 'it' QJ ln FIGURE 3, there is shown 'another embodiment of the invention. The reed relay, generally indicated 36, comprises the solenoid l1 and reed switch 14 constructed and arranged substantially as shown and described in connection with the reed relay litt. ln this form of the invention, the adjusting member is a strip 3l of a soft magnetic nickel-iron alloy disposed between the inner surface of the solenoid ll and the envelope l5 of the reed switch. The adjusting member 3l is provided with a boss, bend, or similar deformation 32 at an appropriate point along its length, preferably adjacent the end thereof reoeived in the coil, to engage resiliently between the coil and the envelope and provide a frictional engagement of the adjusting member in the space between the coil and the envelope of the reed switch. The other end of the adjusting member 31 may projeot outwardly of one end of the solenoid, as shown at 33, this end portion being cut olic at any desired point, or alternatively bent against the end of the solenoid as shown in dotted lines to help retain the member 3l in adjusted position. ln the present instance, the adjusting member is shown as disposed in engagement with the reed switch envelope l5, the bend or projection 32 engaging the inner surface oi the solenoid, but it will be understood that this Iarrangement might be reversed, with the adjusting member lying against the inner surface of the solenoid and the boss or projection 32 extending radially inwardly to engage against the reed switch envelope. It will also be apparent that the main portion of the adjusting member 3l might be disposed intermediate the coil and envelope by appropriately forming the bend or deformation 32. to engage both the coil and the envelope.

lt will be apparent that adjustment of the operating characteristics of the relay 3@ is effected by the adjusting member 3l in substantially the same manner as described in connection with the adjusting member 2h of the relay lt). The member 3l is moved to the desired position relative to the reed switch M and the contact members lo thereof by a simple manual operation. Upon reaching the position corresponding to the desired operation of the relay, it is secured by the frictional engagement of the bend, boss, or projection 32 with the coil and the switch envelope as already described, together with the retaining etect of the end portion 33 of the adjusting member, if it be bent against the coil as described. The adjusting member may be moved to another position relative to the reed switch, if desired, merely by grasping the outer end portion 33 thereof, after straightening the same if it has been bent against the solenoid, and pushing or pulling .the adjusting strip 3l in one direction or the other to the new position, alter which the end portion 33 may again be bent against the end of the solenoid. As in the relay l0, the adjusting member ser es as a shunt diverting a portion of the magnetic flux generated by the solenoid into a path other than that which is partly delined by the contact members lo of the reed switch.

ln FIGURE 4, a reed relay generally designated as all is disclosed, which is substantially identical to the relays l@ and Btl described hereinabove in the structure and arrangement of the solenoid lil and the reed switch ln this embodiment of the invention, the adjusting member (tl is in the yform of a strip or rod 4l of magnetic material such as already mentioned, An outer end of the adjusting member il projects through a suitable aperture in a bracket secured on the base l adjacent the end of the solenoid ll so that the adjusting member may be shifted longitudinally of the reed switch envelope 15' until it is brought to the position corresponding to the desired operation of the contact members lo of the relay. The adjusting member is then secured in this position by soldering the outer end thereof to the bracket ft2, is indicated at 43, any excess length of the member tl protrtding from the solenoid ll being severed. lt will be understood that of course other means than solder might be employed to secure the adjusting member il in the desired position, as a clamping arrangement or a tack weld. The adjusting member il is shown as having its inner end portion bent radially inwardly relative to the envelope l5 of the reed switch so as to lie closely adjacent thereto, while the outer end portion is disposed adjacent the inner surface of the solenoid ll.. lt is to be understood that this is illustrative, and that the entire length of the adjusting member paralleling the envelope l5 might be disposed closely adjacent the envelope, closely adjacent the inner surface of the coil, or at any desired intermediate location, by appropriately bending the adjusting member 4l at any suitable point. The etlect of the adjusting member il is substantially the same as that of the adjusting members Ztl and 3l heretofore described, in providing a part of a flux circuit shunting the reeds or contact members lo of the reed switch t4, to cause diversion of a portion of the flux, or a deilection of a portion of the solenoid iield, from the contact members lo so as to control the operation thereof.

A reed switch lid for use in a reed relay arrangement such as those illustrated in FlGURES l to 4 inclusive, having the sealed envelope l5 with the contact members lo 'serein connected to external conductors or leads l?, is illustrated in FIGURES 5 and 6 with an adjusting member Sil secured thereon. The member dit is formed of a highly permeable nickel-iron alloy of low residual characteristics, similar to the adjusting member 2li, lt is also similar to the member 2@ in form, comprising a strip of the magnetic material disposed on the exterior of the reed switch envelope l5 and having at one end a split ring portion Slt, preferably integral therewith, embracing the envelope. The portion 5l is shown as shorter or narrower than the split ring portion 2l of relay The adjusting member is moved along the envelope to the position effecting the desired relay operation, and is secured on the envelope in that position by any suitable means. In the present case, the adjusting member 5t) is iixed in a desired position by secure clamping of the branches of the split ring portion Sl about the envelope, and securing the split ends of the portion Sl together, as indicated at S2, as by cold solder, an epoxy adhesive, or other suitable means. The adjusting member Sti might be otherwise secured on the envelope l5, as by means of a suitable adhesive tape wrapped around the strip and envelope, or other simple and inexpensive means to hold the adjusting member in its adjusted position. The split ring portion 5l may in some cases be omitted, although it is advantageous to employ some means Vat least partially straddling the envelope l5 in order to guide movement of the adjusting member longitudinally therealong. it will be understood that if desired the adjusting member may be provided with means spacing it in desired radial or lateral relation to the reeds or Contact members le, outwardly of the envelope l5, any of a great number of expedients being available for this purpose.

The reed switch la with the adjusting member 5@ secured in adjusted position thereon may be supplied to meet particular specifications as to operating char* acteristics when employed with a solenoid of given winding, resistance, and other characteristics. Each switch unit including the reed switch ltd and adjusting member Sti may be brought to the desired adjusted relation by subjection to the iield of a solenoid having the specified construction and characteristics, and secured in the adjusted relation providing the desired response to the solenoid energization. lt may then be furnished to a consumer for assembly and use with a solenoid of the given characteristics, with the assurance that the completed relay will operate in the manner desired.

lt is contemplated that other means than the magnetic-metal members disclosed hereinabove may be used for adjustment of reed relays, as for example magnetic arr/epos tape adhesively securabie on the switch envelope and removable for securement in another position, so long as the requisite flux-diverting or shunting effect is provided.

Another reed relay @il is shown in FIGURE 7 as con prising a solenoid 61 of elliptical cross section mounted on a base 13, as by means of the casing 19, 19a disclosed in connection with the relay 10. Mounted in spaced parallel relation within the solenoid is a pair of reed switches 1d of the construction already disclosed, along the envelope of each of which is slidable a shunt of adjusting member 20 having a split ring portion 21 embracing the envelope. The adjusting members are movable along their respective switches 1.4 by any suitable means, as for example the arrangement employed in the embodiment illustrated in FGURE l.

Adjustment of the relay till is basically the same as in the case of the earlier-described relays, but because a plurality of reed switches are employed in proximity to each other, there is a magnetic interaction which modifies the operation of each. In the absence of adjusting or shunt members, the closure of one reed switch, slightly ahead of an adjacent switch provides a more permeable path for flux than the still-open adjacent switch, and thus tends to divert ilux from the adjacent reed switch and delay operation thereof. This makes improbable actual simultaneous operation of all the reed switches in a multiple array. The provision of adjusting members according to the present invention permits this condition to be overcome to a considerable extent, by reason of the effect of such members on the flux circuits through the different switches. The adjusting7 members are located relative to the contact gaps of their respective reed switches so as to obtain an optimum balanced effect in operation of the switches by controlling the diversion of flux from one by another. The use of a generally cylindrical or tubular adjusting member or portion, such as the split ring portion 21, augments the control of switch operation. This is eifected by reason both of the increase in the mass of magnetic material provided by such a tubular construction with resulting greater effect on the magnetic luX, and of the encirclement of the switch by the generally tubular member to effect greater magnetic shielding of the associated switch.

The relay 60 with a pair of reed switches 14 demonstrates on a small scale some of the operational problems of plural-switch relays, and the improvement in control and precision thereof afforded by adjustment in accordance with the invention.

It has been found that adjusting members which include portions generally encircling the reed switch, such as the split ring portions 21 and 5l of the members 20 and 50, respectively, or which are of cylindrical or other tubular form substantially throughout the length thereof, have a greater effect in shunting or bypassing the reed contacts than adjusting members of generally strip-like form, such as the members 31 and 41 of the relays and 40, respectively. This is not to say, however, that the latter should be replaced by adjusting members largely or even partly encircling the reed switch contacts, since the dierences between different forms of the adjusting or shunt members are matters of degree only, and the form of adjusting member adopted for a particular application is determined by a consideration of various factors. The cylindrical or encircling type of adjusting member, for example, requires that a relatively long portion or element be employed to eX- tend outwardly of the solenoid for purposes of adjusting or locating the tubular portion or member on the switch envelope. A unit employing such an adjusting or shunt member, therefore, requires more space and a larger protective casing than would otherwise be the case. On the other hand, adjusting members which do not embrace or encircle the reed switch are nevertheless effective in providing a shunt or by-pass of the switch contacts to obtain the desired control or adjustment of the relay operation. The speciic form or design of adjusting member employed in any particular application of the invention, accordingly, depends on other factors and circumstances besides the shape of the member.

FIGURE 8 is a graph showing curves of the changes in pull-in and drop-out or release voltages, and the changes in the pull-in time, resulting from regular changes in the positioning or adjustment of the adjusting member, in the case of one typical reed relay utilizing the invention. The uppermost curve, designated Time, is that of the time intervals required for operation of the reed switch after closing of the solenoid circuit, at different positions of the adjusting member along the switch, the indicated values or intervals being read from the scale at the right, calibrated in nulli-seconds. The two lower curves are the voltage curves, indicating values according to the scale at the left side of the graph, given in volts. The upper of these two curves, labeled Pull-ln, represents the voltages required for operation of the reed switch by the solenoid corresponding to different adjustments of the adjusting member or shunt, while the lower of the curves shows the values of the solenoid Voltage at which release or reverse operation of the switch was effected by the solenoid. This lowermost of the curves is designated Drop-Out in the iigure. No curve is given for the times required for the drop-out or reverse operation of the switch at the different adjustments of the shunt or adjusting member, since it has been found that the time remains substantially the same regardless of the adjustment or of the Variation in the drop-out voltage. The data represented in FlGURE 8 were obtained in test operation of a reed relay according to the invention, substantially identical to the relay l0 illustrated in FIGURES 1 and 2, employing a Hamlin solenoid having 1,000 turns and a resistance cf 600 ohms, assembled with a Hamlin 62-44, DRG-'2 reed switch. A shunt or adjusting member substantially the same as the member 20 of the drawings was adjusted along the reed switch envelope by means of a bracket-supported screw substantially as illustrated in FIGURE 1. The adjusting member was located at seven positions along the switch envelope, spaced 0.10" apart, beginning with a position substantially like that illustrated in FIGURE 1, with the split ring portion 21 substantially centered relative to the contact end portions of the contact members of the switch, each of the next six positions being successively 0.10" farther to the left as viewed in FIGURE 1. The positions are indicated by the numerals 1 to 7 inclusive at the bottom of the graph.

From the graph, it will be evident that in position 1 the shunt or adjusting member has a maximum effect in diverting flux from iiow through the switch contacts, with the result that a higher pull-in voltage must be applied to the solenoid to effect operation, in this case closing, of the switch contacts, the greater voltage producing a more intense field so that the proportion of the flux following a circuit through the contact members of the switch reaches a density sufficient to draw the contact members together, as would be the case with a lower voltage in the absence of the adjusting member. As the position of the adjusting member is changed by successive movements thereof to the left as already explained, the adjusting member diverts successively smaller proportions of the flux from the switch contact members, and successively lower voltages thus are suicient to provide the flux value needed in the contact members to cause the actuation thereof. in the particular instance represented in the graph of FIGURE 8, the pull-in voltage decreases from approximately 6.9 volts to about 4.65 volts between the rst and seventh positions of the adjusting member. In the same manner, the drop-out, reversing, or release voltage necessary for reverse actuation of the Witch decreases successively with the changes in positionng of the adjusting member, in this case dropping from about 4.9 to about 3.28 volts. The time interval between energization of the solenoid and closing of the switch contacts by the action of the resulting magnetic iield thereon also decreases successively with the movement of the adjusting member from one position to the next, as shown by the Time curve. Specifically, the time required decreases from slightly more than 2 milliseconds to 1.3 milliseconds. The time for reverse operation of the reed switch is not plotted, since as already explained it remains substantially constant. lt may be noted here that if the pull-in voltage is raised to a value considerably above that sufcient to cause actuation of the relay, the time required for response of -the reed switch to energization of the solenoid remains substantially constant regardless of the adjustment of the adjusting member along the reed switch, due to the overriding eiiect of the powerful field generated. It Will be apparent that small changes in the position of the adjusting member resuit in changes in the operating characteristics of the relay which are very great in relation to the increments of movement of the adjusting member. Thus, the voltages and the time all fall to about two-thirds of their peak values as the result of only slight total movement of the adjusting member. lt is therefore possible to obtain very precise adjustment of the relay by means of a suitable adjusting member employed as disclosed hereinabove, and similarly to attain the other advantages and objects of the invention.

It may be pointed out that if the successive adjustments had begun with the adjusting member farther to the right as viewed in FIGURE l, the plotted curves would include values lower than the maximum values lshown in the graph of FIGURE 8, rising from a low to the values plotted for position l as peaks. These additions to the curves actually shown would not be mirror reversals or duplicates of the curves illustrated, however, since the strip-like portion of the adjusting member extending from 'the split ring portion to the exterior of the solenoid would cause a somewhat different effect of the adjusting member on the flux or field, and thus modify the values resulting from positioning beyond position 1.

The use of shunt or adjusting members actually increases the sensitivity of relays, as evidenced by the fact that both the pull-in and drop-out voltages shown in FG- URE 8 can by adjustment of the indicated relay be brought to values lower than the corresponding voltages of the same relay when not provided with the adjusting arrangement. The pull-in voltage of the relay without the adjusting member is 4.8, which is higher than the values for the pull-in voltage provided by location of the adjusting member in either of positions 6 and 7, as evident from reference to FIGURE 8. Similarly, 'the drop-out voltage of the relay when used conventionally, i.e., when not provided with the adjusting member, is 3.5. Again, referring t FIGURE 8, it will be seen that adjustment of the relay by disposition of the adjusting or shunt member in position 7 results in a drop-out voltage of somewhat more than 3.2, well below the unadjusted relay value of 3.5 volts. The relay adjustment thus is not limited to values above those of the conventional or unadjusted relay, but actually provides increased range and sensitivity, since it can result in relay operation and release both at higher and lower voltages than the corresponding conventional or unadjusted reed relay. The lower values, as indicated by reference to the graph in FIGURE 8, occur with the tubular adjusting portion or member relatively remote from the contact gap, as at position 6 or 7. This desirable effect evidently is due to an improved flow of flux through the contacts 16, resulting from the presence ot the shunt or adjusting member, and particularly the tubular portion 21. The adjusting member in the position spaced from the contact end portions of contacts 16 has a concentrating effect on magnetic iiux, gathering in or attracting stray ilux currents passing through air, so as to increase the ilux density. This stronger ux then nds an easier or more permeable path from the adjusting member through the reeds or contacts 16 than through air. Thus a greater magnetic force acts on the contacts at a given solenoid voltage to effect the desired operation of the reed switch than would be the case without the presence of the adjusting member, with the lines of force in a normal relatively divergent pattern, that is, with the ilux relatively dissipated. In the latter case, a higher voltage is necessary in order to obtain at the contact end portions the value of magnetic flux effective to cause operation of the switch.

Increased range and sensitivity of the relay are also provided by the shroud or casing 19 which with its included plate 19a encircles the solenoid 11, as illustrated in FGURES l and 2, these eifects being produced in much the same manner as in the case of the adjusting member. The highly permeable material of the casing provides exteriorly of the solenoid an easier or preferred path for magnetic liux generated by the solenoid upon being energized, as compared to air, and one which is also shorter, so as to cause concentration of the flux in iiowing to the center of the coil. This relatively concentrated or dense ilux then finds an easier-than-air, or more permeable, path through the adjusting or shunt member Ztl and contacts 'i6 to the exterior of the solenoid, and a magnetic force antiicient to eiect operation of the reed switch 14 is applied to the contacts. This eiective force is provided by a solenoid operating voltage lower than would be required if the density-increasing effect of the casing 19 were not involved. The casing 19 may, as indicated, be employed in addition to or in conjunction with the adjusting member, whether the latter comprises a split ring or tubular portion or not.

The casing 119, if used, has an ei'lect additional to, but relatively less than, that of the casing 19 in improving the magnetic ilux coupling internally of the solenoid. Still other casings of magnetic material might be provided exterior-ly of the casings 19 and 11%, if desired, but would be more effective as shields than as flux-directing means, as will be appreciated.

Both the casing 19 and casing 119 act to shield the relay from the efiects of adjacent external magnetic or electrostatic tields, in the conventional manner. A greater number of such magnetic material casings may be used it desired, a plurality of casings in spaced relation being more effective for such shielding than a single thickwalled shield, but the present invention is not directly concerned with such shielding.

in the foregoing disclosure, the magnetic shunt or adjusting member has been shown and described as movable along or relative to the reed switch, which has been disclosed as ixed. it will be evident that movement of the adjusting member relative to the switch necessarily implies or involves movement of the switch relative to the adjusting member, or in other Words, the adjusting member and switch are movable relative to each other, it being a matter of indifference to the inventive concept which is actually moved to effect the desired adjustment. Thus, the adjusting member might be fixed and the reed switch mounted for movement relative thereto, or both might be movably mounted so that either or both might be moved to eiect the adjustment.

For convenience in description, certain positional expressions have been cmployed, but it is to be understood that these refer to the constructions as illustrated in the drawings, and that the relationships of the various parts are not intended to be limited thereby.

It will be understood that the inventive concept disclosed is not intended to be limited to the illustrated embodiments thereof, since various changes and modifications therein may readily be made without departing from the scope of the invention.

We claim:

1. A reed relay comprising a sealed envelope, a pair of magnetic reeds having cooperable Contact regions extending in overlapping relation with each other to form an air gap in said envelope and actuatable by magnetic linx to bring said contact regions together, a solenoid having a central opening encircling at least a portion of the envelope and energizable to provide a magnetic iux which follows a path including said reeds and air gap to actuate said reeds, adjustable means including a member of magnetic material extending along at least a portion ot said envelope within said solenoid opening in a direction generally parallel to the ilux flow including means supported exteriorly l of said central opening connected to said member for moving said member from a rst position directly over said air gap in which said member is operable to provide a maximum reluctance of said magnetic path to a second position toward one end of said envelope in which said member decreases the reluctance of said magnetic path, to a value which is less than the reluctance in said path without said member, whereby an increased range of variable pull-in and drop-out values is obtained.

2. An arrangement as set forth in claim 1 which includes a housing `for said solenoid, and means accessible outside tne housing interior for adjusting movement of said member incrementally to diiferent positions along said envelope.

3. An arrangement as set forth in claim l which includes a magnetic shield surrounding said solenoid to further reduce the reluctance or" said path.

References Cited in the file of this patent UNITED STATES PATENTS 593,230 Moore Nov 9, 1897 936,503 Williams OCt. 12, 1909 2,180,701 Wilson Nov. 21, 1939 2,208,415 Franck et al July 16, 1940 2,289,830 Ellwood July 14, i942 3,035,136 Dal Bianco et al May l5, 1962 3,087,030 Shebanow Apr. 23, 1963 

1. A REED RELAY COMPRISING A SEALED ENVELOPE, A PAIR OF MAGNETIC REEDS HAVING COOPERABLE CONTACT REGIONS EXTENDING IN OVERLAPPING RELATION WITH EACH OTHER TO FORM AN AIR GAP IN SAID ENVELOPE AND ACTUATABLE BY MAGNETIC FLUX TO BRING SAID CONTACT REGIONS TOGETHER, A SOLENOID HAVING A CENTRAL OPENING ENCIRCLING AT LEAST A PORTION OF THE ENVELOPE AND ENERGIZABLE TO PROVIDE A MAGNETIC FLUX WHICH FOLLOWS A PATH INCLUDING SAID REEDS AND AIR GAP TO ACTUATE SAID REEDS, ADJUSTABLE MEANS INCLUDING A MEMBER OF MAGNETIC MATERIAL EXTENDING ALONG AT LEAST A PORTION OF SAID ENVELOPE WITHIN SAID SOLENOID OPENING IN A DIRECTION GENERALLY PARALLEL TO THE FLUX FLOW INCLUDING MEANS SUPPORTED EXTERIORLY OF SAID CENTRAL OPENING CONNECTED TO SAID MEMBER FOR MOVING SAID MEMBER FROM A FIRST POSITION DIRECTLY OVER SAID AIR GAP IN WHICH SAID MEMBER IS OPERABLE TO PROVIDE A MAXIMUM RELUCTANCE OF SAID MAGNETIC PATH TO A SECOND POSITION TOWARD ONE END OF SAID ENVELOPE IN WHICH SAID MEMBER DECREASES THE RELUCTANCE OF SAID MAGNETIC PATH, TO A VALUE WHICH IS LESS THAN THE RELUCTANCE IN SAID PATH WITHOUT SAID MEMBER, WHEREBY AN INCREASED RANGE OF VARIABLE PULL-IN AND DROP-OUT VALVES IS OBTAINED. 